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Editorial: Innovative Technologies and Clinical Applications for Invasive and Non-invasive Neuromodulation: From the Workbench to the Bedside.
Foreground removal requirements for measuring large-scale CMB B-modes in light of BICEP2
The most convincing confirmation that the B-mode polarization signal detected
at degree scales by BICEP2 is due to the Cosmic Microwave Background (CMB)
would be the measurement of its large-scale counterpart. We assess the
requirements for diffuse component separation accuracy over large portions of
the sky in order to measure the large-scale B-mode signal corresponding to a
tensor to scalar ratio of r=0.1-0.2.
We use the method proposed by Bonaldi & Ricciardi (2011) to forecast the
performances of different simulated experiments taking into account noise and
foreground removal issues. We do not consider instrumental systematics, and we
implicitly assume that they are not the dominant source of error. If this is
the case, the confirmation of an r=0.1-0.2 signal is achievable by Planck even
for conservative assumptions regarding the accuracy of foreground cleaning. Our
forecasts suggest that the combination of this experiment with BICEP2 will lead
to an improvement of 25-45% in the constraint on r.
A next-generation CMB polarization satellite, represented in this work by the
COrE experiment, can reduce dramatically (by almost another order of magnitude)
the uncertainty on r. In this case, however, the accuracy of foreground removal
becomes critical to fully benefit from the increase in sensitivity.Comment: 8 pages, 3 figures, 1 table. Accepted by MNRA
A stochastic model for the stepwise motion in actomyosin dynamics
A jump-diffusion process is proposed to describe the displacements performed
by single myosin heads along actin filaments during the rising phases. The
process consists of the superposition of a Wiener and a jump process, with
jumps originated by sequences of Poisson-distributed energy-supplying pulses.
In a previous paper, the amplitude of the jumps was described by a mixture of
two Gaussian distributions. To embody the effects of ATP hydrolysis, we now
refine such a model by assuming that the jumps' amplitude is described by a
mixture of three Gaussian distributions. This model has been inspired by the
experimental data of T. Yanagida and his co-workers concerning observations at
single molecule processes level.Comment: 9 pages, 4 figure
A chemically driven fluctuating ratchet model for actomyosin interaction
With reference to the experimental observations by T. Yanagida and his
co-workers on actomyosin interaction, a Brownian motor of fluctuating ratchet
kind is designed with the aim to describe the interaction between a Myosin II
head and a neighboring actin filament. Our motor combines the dynamics of the
myosin head with a chemical external system related to the ATP cycle, whose
role is to provide the energy supply necessary to bias the motion. Analytical
expressions for the duration of the ATP cycle, for the Gibbs free energy and
for the net displacement of the myosin head are obtained. Finally, by
exploiting a method due to Sekimoto (1997, J. Phys. Soc. Jpn., 66, 1234), a
formula is worked out for the amount of energy consumed during the ATP cycle.Comment: 15 pages. 1 figur
Forecast B-modes detection at large scales in presence of noise and foregrounds
We investigate the detectability of the primordial CMB polarization B-mode
power spectrum on large scales in the presence of instrumental noise and
realistic foreground contamination. We have worked out a method to estimate the
errors on component separation and to propagate them up to the power spectrum
estimation. The performances of our method are illustrated by applying it to
the instrumental specifications of the Planck satellite and to the proposed
configuration for the next generation CMB polarization experiment COrE. We
demonstrate that a proper component separation step is required in order
achieve the detection of B-modes on large scales and that the final sensitivity
to B-modes of a given experiment is determined by a delicate balance between
noise level and residual foregrounds, which depend on the set of frequencies
exploited in the CMB reconstruction, on the signal-to-noise of each frequency
map, and on our ability to correctly model the spectral behavior of the
foreground components. We have produced a flexible software tool that allows
the comparison of performances on B-mode detection of different instrumental
specifications (choice of frequencies, noise level at each frequency, etc.) as
well as of different proposed approaches to component separation.Comment: 7 pages, 2 tables, 1 figure, accepted by MNRA
Lyapunov functions for a non-linear model of the X-ray bursting of the microquasar GRS 1915+105
This paper introduces a biparametric family of Lyapunov functions for a
non-linear mathematical model based on the FitzHugh-Nagumo equations able to
reproduce some main features of the X-ray bursting behaviour exhibited by the
microquasar GRS 1915+105. These functions are useful to investigate the
properties of equilibrium points and allow us to demonstrate a theorem on the
global stability. The transition between bursting and stable behaviour is also
analyzed.Comment: Published on International Journal of Non-Linear Mechanics, vol. 88,
pp. 142-14
Towards the Modeling of Neuronal Firing by Gaussian Processes
This paper focuses on the outline of some computational methods for the
approximate solution of the integral equations for the neuronal firing
probability density and an algorithm for the generation of sample-paths in
order to construct histograms estimating the firing densities. Our results
originate from the study of non-Markov stationary Gaussian neuronal models with
the aim to determine the neuron's firing probability density function. A
parallel algorithm has been implemented in order to simulate large numbers of
sample paths of Gaussian processes characterized by damped oscillatory
covariances in the presence of time dependent boundaries. The analysis based on
the simulation procedure provides an alternative research tool when closed-form
results or analytic evaluation of the neuronal firing densities are not
available.Comment: 10 pages, 3 figures, to be published in Scientiae Mathematicae
Japonica
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